pregnancy and mercury

Mercury is a highly toxic element with deleterious effects on every system in the body. It easily enters the body but is quite tricky to remove.

The window between preconception and early infancy is particularly critical when it comes to mercury exposure, and the toxic connections between fertility, pregnancy, and mercury can last a lifetime.

Mercury present in the mother or father can negatively impact the baby’s genetic expression, while mercury in the mother’s body can accumulate in the baby during pregnancy and breastfeeding. Even low amounts of mercury in babies and young children can lead to neurological delays (1).

Knowing the basics about pregnancy and mercury exposure can help you take precautions. If you are planning a pregnancy, you can time conception in such a way as to protect your baby from mercury.

Be aware that we all have some mercury accumulation in our bodies—it’s inevitable. However, developing fetuses are much more susceptible to the effects of mercury than the rest of the population. 

Remember, this article is not to alarm you! Instead, the goal is to empower you with information you can use to reduce your and your baby’s mercury exposure. 

Pregnancy and mercury exposure

For most people, the most significant sources of mercury exposure are dental amalgam (silver-colored fillings) and fish consumption. 

Because mercury is passed on from mother to child, it accumulates from one generation to the next. So even if you’ve never had amalgam fillings, you may still have a significant mercury body burden from the fillings your mother and even your grandmother had before you were born. Remember that these fillings have been used for about 150 years, and so have affected, and will affect, humans for several generations.

We might also encounter mercury in vaccines, over-the-counter medications, makeup, and occupational exposures such as cement factories. 

Food sources of mercury

The most significant food source of mercury is large, primarily saltwater fish such as: 

  • Swordfish
  • Shark
  • Tilefish
  • King mackerel 
  • Tuna
  • Marlin
  • Orange roughy
  • Chilean sea bass

The Environmental Working Group offers a fantastic guide to seafood consumption, including a seafood “calculator” that considers details such as age, sex, and history of heart disease before creating a customized list of recommendations based on mercury levels. Shark, swordfish, and orange roughy top the EWG’s high mercury “avoid” list.

A note about cilantro

Cilantro leaf contains a substance that chelates heavy metals, including mercury. I don’t recommend eating it in large amounts during preconception, pregnancy, or postpartum/lactation, though it’s okay as a garnish. 

Avoid making cilantro-heavy soups and smoothies, and stay away from any cilantro-based supplements. Some sources contraindicate cilantro during pregnancy altogether. Coriander seeds do not have the same effect as cilantro leaf, so you can use them in your regular cooking and eating routines within reason.

Dental amalgams

A 2022 study examining data from 158 million Americans found a significant correlation between the number of dental amalgams and urinary mercury (3). Other studies have discovered that levels of mercury in the placenta, breast milk, and cord blood increase alongside increased amalgam fillings and fish intake in the mother (4, 5, 6, 7). 

Some countries, such as Germany, strongly recommend against the use of dental amalgams in children and are actively working to reduce the use of amalgams in all populations (8). In the United States, a 2020 FDA safety communication warned that certain people, such as children, pregnant women, or women planning on becoming pregnant, may be at greater risk of mercury exposure due to amalgam fillings (9). 

Further, It may be wise to delay conception by approximately six months if you have recently undergone amalgam removal. The extraction of amalgam fillings can lead to increased levels of mercury for many months, depending on your body’s ability to effectively remove the released mercury (10).

Factors that increase mercury off-gassing from amalgam fillings

Gum-chewing and tooth-grinding exponentially increase the off-gassing of mercury from amalgam fillings. Tooth grinding may happen at night, so be sure to ask your dentist if she notices signs of grinding or your partner if they can hear you click or grind your teeth.

And, logically, the more silver-colored fillings you have, the more mercury will be released.

Research studies suggest that electromagnetic radiation from cell phones or MRI machines, for example, may increase the release of mercury vapor from amalgam fillings. There are several articles on the topic, but this one by Mortazavi and Mortazavi is a good starting point for learning more. 

Pregnant and breastfeeding mothers need to limit radiation exposure from cell phones, cordless phones, and wireless routers as much as possible for their and their babies health. Do your best to restrict cell phone and cordless phone use, and carry your cell phone in a purse or backpack rather than in a pocket or bra.

Avoid this popular supplement if you have amalgam fillings

A common supplement you should avoid during preconception, pregnancy, and breastfeeding if you have amalgam fillings or ongoing mercury exposure sources is alpha lipoic acid (also known as lipoic acid or thiotic acid). 

Alpha lipoic acid is often used in antioxidant, blood-sugar regulation, and liver support products. It’s even in the popular immune-supporting product, Emergen-C®. Unfortunately, because it’s a chelator, alpha lipoic acid can have the unwanted effect of stirring up stored mercury in the mom’s body and exposing the developing fetus to this highly toxic metal.

Don’t confuse alpha lipoic acid, which you should avoid, with alpha-linoleic acid, an essential fatty acid in many healthy foods you can safely enjoy throughout all stages of life. Both can be abbreviated as ALA. If you are confused, please ask a knowledgeable practitioner to clarify this.

Less common mercury sources

  • Household products: broken compact fluorescent lightbulbs, broken mercury thermometers
  • Some cosmetics (particularly mascara and skin creams)
  • Living or working near a crematorium, coal-fired power plant, cement plant, gold-mining area (current or former) or other mercury-dependent industries
  • Occupational exposure: dentistry, gold-mining, cement factories, or workplaces with pressure gauges
  • Educational/hobby: Elemental mercury present in chemistry sets
  • Some immunoglobulin, vaccine, and injectable medications—always ask to see the entire product insert (11)
  • Some items that are now banned or exist only in mercury-free versions in the U.S. include mercury thermometers, teething powders containing calomel, the antiseptic merbromin (sold as Mercurochrome®), and contact lens solution—be aware of older versions of these products 
  • Some religious and folk healing rituals use mercury
  • Some sources are still rationalizing the use of mercury in medicinal preparations

Finally, ask your parents and grandparents about mercury exposure in your early childhood and previous generations of your family. Even though some of the above exposure sources are now obsolete, mercury is passed from mother to child and accumulates across generations.

Pregnancy and mercury: plan ahead

Before conceiving a baby, it is a good idea to ask yourself three basic questions regarding mercury exposure:

  1. What is my timeline for pregnancy? How flexible can I be?
  2. What can I do before conception to reduce exposure and body burden?
  3. What can I do throughout pregnancy and breastfeeding to reduce mercury exposure?

Some couples have more flexibility in their timeline than others. The more flexible your timeline, the more proactively you can work before conception. The work you and your partner do before conception to decrease mercury load will increase your fertility, reduce the chances of miscarriage, and improve the health of the sperm and eggs.

Consider safely removing amalgam fillings prior to conception. Remember, you will need to wait a few months after the amalgams are removed before trying to conceive. I use a safe and gentle rebalancing approach to prepare my clients for conception after amalgam removal.

If you do not have amalgam fillings but have a history of significant mercury exposure, you may also want to consider slowly detoxifying before conception. Below are some general tips that are appropriate for everyone: 

  • Increase your protein and colorful, fibrous plant food consumption so these become the majority of your calories. These two food groups are the backbone of our bodies’ detoxification (medically termed “biotransformation”) processes. 
  • Make sure you are hydrated with clean water. A good indicator of proper hydration is light yellow, not clear or dark yellow urine. 
  • Do your best to get quality sleep in a dark, cool room. Additionally, take time to rest and breathe deeply during the day. Detoxification can only happen if we are calm and rested. 

If your preconception timeline is short, focus on preventing new mercury exposures. Conceiving a baby during or shortly after removing or detoxifying mercury may actually increase the amount of mercury that crosses the placenta.



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